JP3240818B2 - Hydraulic equipment for cargo handling of battery-powered industrial vehicles - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a battery type industrial vehicle, and more particularly to a hydraulic device for cargo handling such as a battery type forklift.

[0002]

2. Description of the Related Art For example, a battery-powered forklift is
Although it is suitable for cargo handling work in a building because it does not emit exhaust gas, hydraulic equipment including a lift cylinder, tilt cylinder, etc. is usually used for lifting and lowering of the cargo handling fork and tilting of the mast guiding the fork. Have been. And
A hydraulic pump driven by an electric motor powered by a mounted battery is used to drive the hydraulic oil supplied to and discharged from these cylinders. Since recharging the on-board battery usually requires a considerably long time, various measures have been taken to effectively use the charging energy and lengthen the charging cycle.

[0003] With referring to FIG. 6 an example of a conventional apparatus for the lift control valve 1 in the oil control valve (connected to the port C ₁₎ lift cylinder not shown, connected hydraulic pump (the port P ) And an oil reservoir tank (connected to port T). Further, the tilt control valve 3 having a port for communicating with the lift control valve 1 is connected to _two pressure chambers (not shown) of the tilt cylinder (connected respectively to the ports C ₂ and C ₃ ) and an oil reservoir tank (T). You have a port to A restrictor 7 is provided in an oil passage 5 that directly connects the hydraulic pump (P) and the oil reservoir tank (T).

In a conventional apparatus having such a hydraulic circuit, when the lift control valve 1 is moved to a raised position by a control lever, hydraulic oil from a hydraulic pump (T) is supplied to a lift cylinder (C ₁ ) and a fork is provided. Is raised to the other lower position, the hydraulic fluid discharged from the lift cylinder (C ₁ ) is returned to the oil reservoir tank (T). Then, when the lift control valve 1 is selected to the neutral position, the connection state as shown in the figure is established, and the hydraulic oil discharged from the hydraulic pump (P) passes through the throttle 7 to the oil reservoir tank (T).
Head to.

[0005] Further, when the tilt control valve 3 is selected to the forward or backward tilt position, the hydraulic oil bypassing the lift control valve 1 is selected to the two pressure chambers (C ₂ , C ₃ ) of the tilt cylinder. is supplied, the hydraulic oil discharged from the one pressure chamber (C ₂ or C ₃₎ is returned to the oil reservoir tank (T). When the tilt control valve 3 is selected to the neutral position, the connection state is as shown in the figure.

That is, the lift control valve 1 and the tilt control valve 3
However, if both are selected to be in the neutral position, the hydraulic circuit will be in the connection state as shown. The relationship between the lever opening (opening 0 is a neutral position) of each control lever (not shown) of each of the control valves 1 and 3 and the output torque of the hydraulic pump motor is shown in the characteristic graph of FIG. Thus, when the lever opening becomes 0 (zero), the discharge hydraulic oil receives the resistance of the throttle 7 and the hydraulic pump stops.

[0007]

As described above, in the conventional apparatus, a throttle is provided in an oil passage from the hydraulic pump to the oil reservoir tank, and when the control lever is in the neutral position, the pump is operated by the hydraulic resistance caused by the throttle. Is stopped immediately, so that the energy of the hydraulic pump becomes heat and is dissipated. Therefore, the present invention eliminates the above-mentioned disadvantages,
An object of the present invention is to provide an efficient hydraulic device for cargo handling of a battery-type industrial vehicle that has substantially no energy loss.

[0008]

In order to achieve the above-mentioned object, a hydraulic apparatus for cargo handling of a battery-type industrial vehicle according to the present invention comprises a lift cylinder for raising and lowering a cargo handling member, and a tilt cylinder for tilting the cargo handling member. A hydraulic pump that drives the hydraulic oil supplied to and discharged from the lift cylinder and the tilt cylinder, a motor that drives the hydraulic pump with electric power from a battery, and a flow of the hydraulic oil that is supplied to and discharged from the lift cylinder and the tilt cylinder. In a hydraulic apparatus for cargo handling of a battery-operated industrial vehicle having a lift control valve and a tilt control valve for controlling respectively, the lift control valve is selected to a neutral position.
Lift switch and tilt control valve
A tilt switch for detecting that it has been selected to be in the vertical position,
A rotation sensor for detecting that the motor is rotating;
Motor according to the control position of the shift control valve and the tilt control valve
Control rotation, lift switch and tilt switch
Lift control valve and tilt control valve respectively
It is detected that the neutral position has been selected and the rotation sensor
Motor is detected when the motor is rotating.
And a controller for performing regenerative braking.

[0009]

In the above construction, the hydraulic pump driven by the electric motor discharges the hydraulic oil, while the lift control valve and the tilt control valve whose positions are selected by the control lever respectively communicate with the lift cylinder and the tilt cylinder. Form an oil passage. In this way, the hydraulic oil discharged from the hydraulic pump is supplied to and discharged from the lift cylinder and the tilt cylinder through the formed oil passage, and the cargo handling member such as a fork is raised or lowered or tilted. Select both the neutral position of the lift control valve and <br/> tilt control valve (lever turning degree 0)
The lift switch and tilt switch
The rotation sensor detects that the motor is rotating.
When the controller detects that the motor has been regenerated, the controller regeneratively brakes the motor to stop the motor .

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the drawings, the same reference numerals indicate the same or corresponding parts. In FIG. 1, the cargo handling hydraulic device 10 mainly includes a hydraulic pump 11, an electric motor 13 for driving the hydraulic pump 11, an oil reservoir tank 15, a tilt cylinder 17, a lift cylinder 19, and an oil control valve 40 constituting a main hydraulic circuit. Be composed. Further, these components include hydraulic piping 21, 2
3, 25, 27, 29 and 31 are individually communicated.
The return filter 35 at the tip of the hydraulic pipe 23 is provided so as to be immersed in the oil in the oil reservoir tank 15.

When the operation of the cargo handling hydraulic device 10 shown in FIG. 1 is roughly described, the hydraulic oil in the oil reservoir tank 15 is sucked into the hydraulic pump 11 through the suction filter 33 and the hydraulic piping 21. The hydraulic pump 11 is driven by an electric motor 13 using a battery (not shown) as a power source. The hydraulic oil whose pressure has been increased is supplied to an oil control valve 40 through a hydraulic pipe 25. The lift cylinder 19 is controlled through the hydraulic pipe 27 under the control as described later.
The hydraulic oil supplied to the cylinder extends the lift cylinder 19,
Raise a not-shown fork (loading member). Also,
Since the weight of the fork and the weight of the load on the fork are always applied to the lift cylinder 19, if an oil path is formed, the hydraulic oil returns to the oil reservoir tank 15 through the hydraulic piping 27, 23 and the return filter 35.

Similarly, the hydraulic oil whose flow is controlled by the oil control valve 40 as described later is supplied to the tilt cylinder 17 through one of the hydraulic pipes 29 and 31 and passes through the other of the hydraulic pipes 29 and 31. Is discharged. That is, the tilt cylinder 17 expands and contracts, and controls the mast that guides and supports the fork to a tilted forward or backward position.

FIG. 2 shows a hydraulic circuit of the oil control valve 40. As shown, spools forming a lift control valve 41 and a tilt control valve 43 are provided.
Selects and controls the position. Actually, the control levers 45 and 47 are arranged in a form as shown in FIG. 1 and operated by an operator. Lift control valve 41
Is controlled by the control lever 45 so as to take the ascending, descending, and neutral positions, and the neutral position (lever opening is zero)
Then, an oil passage as shown is formed. That is, the hydraulic oil that has entered the port P from the hydraulic pump 11 through the hydraulic pipe 25 passes through the lift control valve 41 and the tilt control valve 43 and reaches the port T through the oil passages 49 and 51. Port T
The hydraulic oil that has flowed out returns to the oil reservoir tank 15 through the hydraulic piping 23.

[0014] Those skilled in the art, so that it can be easily predicted, the control lever 45, when moved to the raised position, the hydraulic fluid exits to port C _1, the lift cylinder 19
And the lift cylinder 19 raises the fork and the load. Conversely, the control lever 45, when moved to the descending side beyond the neutral position, the port C ₁ communicates with the oil passage 53 and 51. Thereby, the lift cylinder 1
9 is discharged and returns to the oil reservoir tank 15 through the port T and the hydraulic piping 23.

The selected position of the control lever 45 as described above is detected by a limit switch (not shown) or a detector of an operation amount sensor, and is used for controlling the electric motor 13 as described later.

Similarly, the control lever 47 whose position is detected moves the spool of the tilt control valve 43,
The bypass oil passage 55 is connected to, for example, the port C ₂ , and the port C ₃ communicates with the oil passages 53 and 51. This way,
Hydraulic oil from the hydraulic pump 11, flows in the order of the tilt control valve 43 → the port C ₂ → hydraulic pipe 29, enters into the tilt cylinder 17 and allowed to shorten it. This way,
The mast (not shown) tilts backward, and the tip of the fork rises with respect to the base end. Hydraulic oil in another pressure chamber of the tilt cylinder 17 is pushed out, and the port C ₃ → the tilt control valve 4
It flows in the order of 3 → oil passage 53, 51 → port T, and returns to the oil reservoir tank 15. Similarly, the bypass oil passage 55
If it caused to connect to the port C _3, supporting the fork, mast for guiding the inclined forward.

FIG. 3 is a conceptual diagram of a rotation control system of the electric motor 13. The battery 61 is electrically connected to the electric motor 13 via an electric controller or controller 63, and the controller 63 controls the direction and value of the current. Motor 13
A rotation sensor 65 such as a pick-up coil attached to the control levers 45 and 47 (see FIG. 2).
The lift switch 67 and the tilt switch 67 for detecting the selection or the operation position of are respectively electrically connected to the controller 63. The operation of the braking circuit included in the controller 63 is shown in the flow chart of FIG. 4, but the specific details of the braking circuit itself are omitted because it would be possible for a person skilled in the art to predict from this flowchart.

As shown, the control lever 4
5 and 47 are in the neutral position, the lift switch 67 and the tilt switch 69 are both OFF, and the motor 13
If the rotation of the motor 13 is not stopped (the rotation speed N> 0), the operation of the electric motor 13 enters the regeneration mode and is braked. The relationship between the control levers 45 and 47 and the output torque of the electric motor 13 is shown in FIG.

[0019]

As described above, according to the present invention, the lift control valve for controlling the lift cylinder and the tilt control valve for controlling the tilt cylinder are each in the neutral position.
And the electric motor driving the hydraulic pump is rotating
At this time, the controller performs regenerative braking of the electric motor, so that energy loss can be prevented.

[Brief description of the drawings]

FIG. 1 is an overall system diagram of an embodiment of a hydraulic device for cargo handling according to the present invention.

FIG. 2 is a hydraulic circuit diagram showing a part of the cargo handling hydraulic device according to the embodiment of FIG. 1;

3 is an overall conceptual diagram of a main part of the hydraulic circuit of FIG. 2;

FIG. 4 is a flowchart illustrating an operation of a main part of the hydraulic circuit shown in FIG. 3;

FIG. 5 is a characteristic diagram of an electric motor included in the hydraulic circuit of FIG.

FIG. 6 is a hydraulic circuit diagram of a conventional device.

FIG. 7 is a characteristic diagram of a motor included in a conventional device.

[Description of Signs] 10 ... Hydraulic device for cargo handling, 11 ... Hydraulic pump, 13 ... Electric motor, 15 ... Oil reservoir tank, 17 ... Tilt cylinder, 19 ... Lift cylinder, 40 ... Oil control valve, 41 ... Lift control valve, 43 ... Tilt control valve, 4
5 ... control lever, 47 ... control lever,
49 ... oil passage, 51 ... oil passage, 53 ... oil passage, 55 ... bypass oil passage, 61 ... battery, 63 ... electric controller.

Claims (1)

(57) [Claims] 1. A lift cylinder for raising and lowering a loading member, a tilt cylinder for tilting the loading member, a hydraulic pump for driving hydraulic oil supplied to and discharged from the lift cylinder and the tilt cylinder, and a hydraulic pump For loading and unloading a battery-type industrial vehicle, comprising: an electric motor that drives a pump with electric power from a battery; and a lift control valve and a tilt control valve that respectively control the flow of the hydraulic oil supplied to and discharged from the lift cylinder and the tilt cylinder. In the hydraulic device, it is detected that the lift control valve has been selected to the neutral position.
A lift switch for detecting that the tilt control valve has been selected to the neutral position.
Tilt switch and a rotation sensor for detecting that the electric motor is rotating
And the control position of the lift control valve and the tilt control valve
While controlling the rotation of the motor, the lift switch
The lift control valve and the chill
Control valves are detected to be in the neutral position.
And that the motor is rotating by the rotation sensor.
Control to regeneratively brake the motor when
A hydraulic device for cargo handling of a battery-type industrial vehicle, comprising: a roller ;